Assistant: Proof-read all scenarios

Originally created by @sajolida on #10545 (Redmine)

Every time I write a new scenario, the contextual CSS tricks might affect all the other ones. So once I’m done with a first writing of all of them I should proof-read them all again and make sure that I didn’t break anything.

• Rewrap some very long lines
• Add DocBook classes
• Use absolute path for all images

Feature Branch: web/105454-proof-read

Parent Task: #9203 (closed)

Related issues

• Blocks #10638 (closed)